AB0326 IMPACT OF ANTI-CITRULLINATED PROTEIN ANTIBODIES AND RHEUMATOID FACTOR ON BONE MINERAL DENSITY CHANGE IN RHEUMATOID ARTHRITIS PATIENTS TREATED WITH DENOSUMAB
Authors: S. Anno, T. Okano, T. Koike, H. Nakamura
Journal: Annals of the Rheumatic Diseases (2023)

<h3>Background</h3> Osteoporosis is one of the major comorbidity in patients with rheumatoid arthritis (RA). A low bone mineral density (BMD), especially in the femoral neck, was associated with the presence of anti-citrullinated protein antibodies (ACPA) and rheumatoid factor (RF). However, there are few reports investigated the influence of autoantibody on BMD change in patients with RA after osteoporosis treatment. <h3>Objectives</h3> There are a lot of evidence that denosumab increased BMD in patients with osteoporosis, and improved bone eroison in patients with RA. We evaluated the BMD change in patients with RA treated denosumab, and assessed the effect of autoantibody, such as ACPA and RF. <h3>Methods</h3> This study included 196 RA patients (187 female; mean age, 71.0 ± 9.0 years; mean disease duration, 17.8 ± 15.3 years; mean DAS28-CRP, 2.9 ± 1.2) who fullfilled the criteria of osteoporosis and treated with denosumab. Disease activity of RA was treated according to EULAR recommendation 2022. BMD at the lumbar spine, proximal femoral and femoral neck were evaluated by dual energy X-ray absorptiometry at baseline and 12 months after denosumab treatment. We evaluated the influence of ACPA and RF for BMD change. <h3>Results</h3> Improvement ratio of BMD at the lumbar spine, proximal femoral and femoral neck were 6.4% (p&lt;0.01), 3.4% (p&lt;0.01) and 1.6% (p=0.10) after 12 months treatment. There were no differences in BMD at the lumbar spine, proximal femoral and femoral neck before denosumab treatment between 101 ACPA-positive patients and 30 ACPA-negative patients (0.77 vs 0.77g/cm<sup>2</sup>, p=0.68; 0.58 vs 0.61 g/cm<sup>2</sup>, p=0.13; 0.48 vs 0.47 g/cm<sup>2</sup>, p=0.7), between 128 RF-positive patients and 42 RF-negative patients (0.75 vs 0.76 g/cm<sup>2</sup>, p=0.47; 0.59 vs 0.59 g/cm<sup>2</sup>, p=0.68; 0.47 vs 0.46 g/cm<sup>2</sup>, p=0.12). Improvement ratio of BMD at the lumbar spine, proximal femoral and femoral neck were 6.1% (p&lt;0.01), 3.6% (p&lt;0.01) and -0.18% (p=0.49) in ACPA-positive patients, 5.8% (p&lt;0.01), 2.3% (p=0.01) and 3.7% (p&lt;0.01) in ACPA-negative patients after 12 months treatment. Although there were no differences between ACPA-positive patients and ACPA-negative patients in BMD change at the lumbar spine (p=0.86) and proximal femoral (p=0.72), BMD change at femoral neck in ACPA-positive patients were lower than ACPA-negative patients (p=0.03). Improvement ratio of BMD at the lumbar spine, proximal femoral and femoral neck were 6.6% (p&lt;0.01), 3.5% (p&lt;0.01) and 1.1% (p=0.47) in RF-positive patients, 6.5% (p=0.04), 2.5% (p&lt;0.01) and 2.0% (p=0.06) in RF-negative patients after 12 months treatment. There were no differences between RF-positive patients and RF-negative patients in BMD change at the lumbar spine (p=0.08), proximal femoral (p=0.66) and femoral neck (p=0.45). Multivariate linear regression analysis revealed that low BMD at baseline (β=-0.35, p&lt;0.01) and ACPA positive (β=-0.2, p=0.04) inhibited the improvement of BMD at femoral neck (table 1). <h3>Conclusion</h3> Denosumab improved BMD at the lumbar spine and proximal femoral in patients with RA independently regardless of ACPA and RF. ACPA-positive patients were difficult to improve BMD at femoral neck despite denosumab treatment. <h3>Reference</h3> [1] Gökhan Sargin et al. Eur J Rheumatol 2019; 6(1): 29-33. <h3>Acknowledgements:</h3> NIL. <h3>Disclosure of Interests</h3> None Declared.